Method for making electrolytic condensers



July 26, 1960 c. WELLINGTON 2,946,727

METHOD FOR MAKING ELECTROLYTIC C'QNDENSERS Filed Oct. 20, 1955 3 Sheets-Sheet 1 INVENTOR CARY L. WELLINGTON BY W4 ATTORNEYS July 26, 1960 C. L. WELLINGTON METHOD FOR MAKING ELECTROLYTIC CONDENSERS Filed Oct. 20, 1955 3 Sheets-Sheet 2 FIG. 7

INVENTOR CARY L. WELLINGTON BY W ATTORNEYS July 26, 1960 c. WELLINGTON METHOD FOR MAKING ELECTROLYTIC CONDENSERS Filed Oct. 20, 1955 3 Sheets-Sheet 3 FIGQ.

FIG. IO.

FIGI I.

i llllk INVENTORI CARY L. WELLINGTON BY ATTYS.

Filed Oct. 20, 1955, Ser. No. 541,626

- 7 2 Claims. (Cl. 204-28) This invention relates'to an improved method 'ofmanufacturinganodes for electrolytic condensers and of assembling the anodes in the condensers. The method is particularly advantageous in condensershavinga plurality of anodes and includes .a method of assembling the anodes into the condenser. This invention also relates to the apparatus employed in practicing the method ta s Patent of the. invention and to the product of themethod, an.

electrolytic condenser.

Electrolytic condensers are usually made using a strip of metal foil as the cathode and at least one strip of metal foil as an anode, each with a terminal tab attachment, rolled into a spiral package with stripsof absorbent insulation separating the anode from the cathode or other anode electrodes. The spiral package is then impregnated and inserted into a container, and the coin tainer is sealed with the terminal tabs either themselves penetrating the container walls or connected to conductors which penetrate the container walls.

There would be conduction between the electrodes through the .electrolye of'the condenser, when potential is applied between its anode and cathode terminals,'were the anode or anodes not formed. in some instances it is desirable to form all electrodes. Forming produces a high quality, high dielectric strength oxide coating on the anode material. The process of forming the anode is usually accomplished prior to the assembly of the. condenser. by introducing the anode foil material into a.

bath consisting of a boricjacid solution or other electrolyte, using the foil as one of two electrodes and ap-' plying a voltage between the electrodes.

Heretofore, it has been common to form the anode materialin sheets, to facilitate handling and then cut the sheets into strips of. desired length for the anode. Thereafter, tabs Which may or may not have been separately formed have been atiixed to the strips in order to provide terminalsforthe particular electrode, and the attachment of a tab to a strip has been usually accom'plishedby some mechanical crimping means; All through these processes and. until thecondenser is completed, the strips have had to be handled extensively and this handling has resulted in bending, rubbing and other effects which damage theoxide coating. As a consequence of the processing and handling after forming, raw edges and bruised and broken oxide covered areashave exposed bare metal-to the electrolyte in the assembled condenser. It has been possible to partially replace the oxide lost by these efiects by passing low currents for long periods through newly v completed electrolytic condensersin order to ,age them. Theoxide coating formed by aging, however, is farinfriorelectrically and less durable mechanically than the oxide; coating produced ,by forming, and, hence,"condensers produced in this way frequently have had a far shorter life than a condenser with an ideal anode completely' covered with formed oxide woul'dhave because of failure of those oxide portions produced by aging.

The present invention is directed to a method of forming' whereby practically the whole of the anode is formed V 2,946,727 Patented- July 26, 196 0,

justprior to its assembly into a condenser so that damage to the formed oxide coating prior to the completion of the condenser is minimized and so that the amount of.- oxide required to be formed by aging is extremely small; The method of the present invention forms anodes for a second time just prior to the time when they are ready for use in the condenser and makes it possible to store; the formed anodes still attached together by small bridges of foil between perforations in the ribbon wound onto;

In handling and placing them in their elec-- trode positions in the condenser only a small amount of damage compared to that which is usual in the prior art;

a mandrel;

methods of handling will occur.

beyond its edge afiixed to it before or after making the:

perforations, but prior to its separation from other an ode portions. A second forming may differ somewhat; from the first which usually takes place in a short time at? relatively high current density. The second forming usually takes place after the anodes are completed and while they remain in a ribbon, either before or. after per forations are made between adjacent anode perforations. In the first forming electrical contact is made with the bare. metal through rollers over which the ribbon passes. In the second forming, however, the oxide coating prevents good electrical contact with the rollers, but in accordance. with the invention one end of the ribbon is conductively attached to a conductive mandrel or reel and remains attached throughout the forming operation. As the ribbon of anodes is passed through the second forming bath, the raw metal and bruised areas. of thewhole'rollare formed using a current density which of necessity is somewhat lower than in the first forming but as high as possible in view of the-formed and/or perforated condition of the ribbon.

The apparatus forassembly of condensers having a" a plurality of rolls are employed, anodes are detached from them in a predetermined sequence. a Each roll con tains a ribbon formed to give its anodes a particular capacitance and voltage rating per unit length at a se lected electrode spacing. Each condenser contains a plurality of these anode's all insulated-from each other,

as well as from the cathode, and each having a diiferent voltage and capacitance rating from the others and these anodes arewound consecutively one. after another opp'o-v site the cathodes into a; spiral package. The presentinventionalso provides apparatus whereby when aplurality of rollsof anode ribbon are employed, the different an--- odesmaybetakenonly in the proper sequence one at. a time so that each condenser wound using the apparatus isprovided with the proper anode electrodes arranged;

in the order specified.

' -For a .better understanding of the present invention;

' reference is made to the following drawings in whichz- Fig. 1 illustrates in section the various tapes or ribbons employed in making. an electrolytic condenser of the present invention;

Fig! 2 is a plan view rant above shows; a coiid'iler" antenna spiral package unrolled to show the difierent anodes in position;

Fig. 3 is a plan view from above of a ribbon of anodes in accordance with the present invention;

Fig, 4'. is an enlarged schematic view showing one method of attaching terminal'tabs to the condenser electrodes;

Fig. 5 is a diagrammatic view representing the way in which a ribbon of anodes is attached to a mandrel for its second forming which is performed in accordance with the present invention;

Fig. 6 is a diagrammatic view showing the. apparatus for assembly of condensers of the present invention;

Fig. 7 is a side-elevational view of the portion of'the.

apparatus of Fig. 6 which holds the various anode ribbons in place; i

Fig. 8 is a view of the structure of Fig. Talongline 8 8 of that drawing.

Fig. 9 is a schematic diagram of one method of processing electrodes in accordancewith the present invention; Fig. 10 shows another method of processing electrodes; and i a Fig. 1.1 shows schematically another method of processing electrodes.

Referring, to Fig. 1, it is common practice in the art to makeelectrolytic condensers by winding strips-of metallic. foil and strips of an absorbent insulator togetherontofanv arbor such that the foilstrips are separated from one an other by theabsorbent strips. The foil strip 11} is a continuous metallic strip of material suchasaluminum and has. affixed to it a tab 11 which provides a cathode terminalfor the, device. preferably only one of several anodes asmay be seen .in

Fig. 2 Anodes 12, 13, i4, and 15 each have a'terminaL tabfld, 17, 18, and 19, respectively, extending transversely of its anode strip and beyond the edge ofthe anode strip, and-each of these terminal tabs is .fixed in a similar position, preferably adjacent to one endof the Between adjacent anode and the cathode anode portion. surfaces are arranged a plurality of absorbentinsulator strips 20, 21', 22 which may be composed of different rna-v terials havingdifferent combinations of desirable properties, such as electrical resistance, electrolyte absorption, wet strength, etc. 25 below the. cathode it) provide insulation between the together on the winding arbor to form a cylindrical pack age.

In accordance with the present invention, a plurality of'likje anodes are made from a single aluminum ribbon. This ribbon 26 is preferably initially formed as ribbon in a boric acid bath in accordance with well known practices to provide an oxide coating over all its surfaces. After forming, the ribbon is perforated at 27 at equal intervals leaving between perforations narrow bridges of material sulficient to .hold portions of the ribbon separated by the perforations together under light tension. Tabs 28 of aluminum foil are next attached in such a way as to make good electrical contact with the ribbon, transverse to each portion to extend beyond an edge of the portion. The tabterminals 28 are advantageously aifixed to'each'portion of the ribbon usinga plurality of pointed punch members .29 (see Fig.4) which are arranged "in'a row to moveupwardthrough a base member 30, to penetrate the ribbon ,Zdand. a tab 28placed in proper position'on top of the ribbon to punch a hole and form a ring flange 31 which is crimped in place by a downwardly moving anvil 32. Thereafter, the ribbon shown in Fig. 3 has one end conductively attached to a mandrel-33 onto which it may be wound into a spiral package 34 as shown in 'Fi'g. 5. The ribbon conductively attached to the mandrelmay be passed through its forming bath as it is wound onto the mandrel and/ or it may be unwound from.

the mandrel to pass through the bath. In. the bath a voltage is..applied between the ribbon throughthe-man- The anode 12 shown in Fig. 1 is.

A similar group of strips 23, 24, and

. 1 15 other surfaces. of the anode and cathode as they are rolled drel and a cathode in the bath, but the current must be limited to an amount sufficiently small to avoid burning part the bridges between adjacent portions of the ribbon. The current which flows through the ribbon will cause oxides of a quality superior to those formed during aging to be formed at all raw edges such as those at the perforations and at the flanges 31. In order to avoid limiting the current the perforations 21 may be made after the second forming, butit will be appreciated that subsequent perforation of the tape will produce additional raw edges which must be formed by aging, thereby acquir ing an inferior oxide coating in that particular area.

It is possible to change the sequence of various steps of the method of the'pre'sent invention. For example, it is possible to form sheets of foil before cutting them into ribbons. And as mentioned, it is possible to attach the tab to the ribbon before forming so that only the perforatingis left to be accomplished before-or after the second forming operation.

toward an arbor 37which is split and accepts the different materials being wound between its parts. The absorbent; 1 insulator tapes 20, 21, and 22 are each supported on'reels 37," 38',"-and 39 and pass over guides 40, 41, and 42, respectively. Similarly, absorbent insulator tapes 23, 24', and are supported reels 43, 4s, and and pass over guides 46;47, and 48, respectively. These absorbent tapes inthe completed condenser have the function of retaining the electrolyte and mechanically separating theelectrodes from one another. All of these tapes are'direc'ted toward the arbor 37 as shown in Fig! 6. The various anode tapes 1'2, 13, 14, and 15 are mounted on reels 47, 48, 49, and 50, respectively, and are arranged" above the tapes as they come to the arbor 'so that they.

may be selected one at a time and placed by hand atop' tape 20 in the course of the winding process. Advantageously, the tapes all pass through the holding device d'livhich not only permits the tape portions to be sepa rated from one anotheralong-their perforations, but advantageously is of such arrangement that the tapes are selected in the order in which they are to be wound in a manner which will hereafter be described. The arbor is driven vbya motor 52which may be belt connected by nected bylinkage 56 to a clutch and braking mechanism permits the arbor to be started or stopped by the pressure ofthe operators foot. y

In the use of the device-of Fig. 6 tapes are taken from the tapes 12, 13, ltd, and 15 in the order shown in Fig. 2

and placed between the portions of the split arbor atop insulator tape 2t) in time for the leading edge of the par ticular anode to be started into the package roll. 'The; arbor is caused to rotate by manipulation of foot pedal 55.

Tapes are successively.

to connect motor 52 to the drive. selected from reels 47, 48, 49, and 50 and portions are torn from each of the tapes 12, l3, l4, and 15, in that order. Each anodetape portion is wound into the-packageas the arbor turns, a space being left between adjacent anodes, and the arbor may be stopped to assure the proper positioning by hand of each anode. Device 51; assures that the handling of the formed anode tapes will producea minimumof damage so that the amount of oxide replacement required by the latter aging processwill become minimized. When the cylindrical package is completed, the arbor is withdrawn and the package is impregnated with electrolyte which is held by the absorbent insulator material and then the package is in-,

sorted into a tubular housing which is next closed at both ends with the terminal tapes either protruding through the enclosure or being connected to appropriate con ductors which extend through the enclosure.

The holding device 51 is shown in Figs. 7 andS. The

device is supported on a support plate 57 which also sup--' belt" connector 53 to a drive 54. A foot pedal 55 con-- ports a plurality of radially arranged wedge shaped blocks 53 fixed to the plate by bolts or other appropriate means. Between the wedge shaped blocks are movable Wedge members 59 which are attached by linkage connections 60 to solenoids 61. Each ofthe blocks 59 isspring-connected by a spring 62 to a common post 63. The block is supported by means such as bolts 64, 65 in a slot 66 passing through plate 57 so that it may move radially up and down. The bolt 64 extends further-bebind the plate than does bolt 65 so that the spring 62 may be attached to it. Accordingly, it may be seen that ordinarily the spring 62 holds its block 59 in place against the fixed blocks 58. the anode tapes 12, 13, 14, and 15 passing between'a movable block 59 and a fixed block 58 will be held in place by the wedging action. Each block 59 is released by energizing of its solenoids 61, and this is advantageously done in such a way that one tape after another is freed in a predetermined order such as 12, .13, 14, 15; 12, 13, etc., so that only the proper tape for the needed anode may be had for adding to the condenser package. Appropriate interlocking devices for assuring that the solenoids will work successively in the desired sequence will occur to one skilled in the art. For example, it is possible to employ two switches in series with each solenoid and the energy source so that one switch will be closed by the action of the previous solenoid and opened by the release of its own solenoid and the other switch will be manually operated and spring loaded fro-automatically open upon release of pressure.

It will be observed that the number of elements employed in the device 51 will depend upon the number of anodes to be used in a particular condenser. Likewise, the nature of the device may be varied considerably as, for example, by putting the wedges between two plates 57 instead of mounting them on only one. The advantage of using wedges on only one plate accrues from the ease of access to the strips whereas mountingthe wedges between two plates may give the device added stability.

Figs. 9, and 11 illustrate various modifications of the process according to the present invention.

Fig. 9 illustrates the preferred process whereby ribbon 26 is provided with tabs 28 and then perforations before being formed, or reformed. As can be seen in Fig. 9, the ribbon comes from a ribbon supply 55 and is drawn therefrom to a 'takeup 56. In the course of its path between these two termini it passes tabbing means 57 at which tabs 28 are afiixed. Thereafter it passes perforating knives 58 which perforate the ribbon between tabs. Finally, it is directed by suitable rollers through tank 59 filled with a conducting electrolyte 60 which electrolyte contains an electrode 61, which isspecifically a cathode. This electrode may be connected to the takeup In this condition, a tape such as 61a and 61b.

The process of Fig. 9 may be modified by omitting either the tabbing or the perforating of the ribbon 26 and may be varied by using either formed or unformed ribbon 26.

Fig. 10 diagrammatically illustrates a modified arrangement whereby tape is first tabbed by tabbing means 57',

then fed through electrolyte 60 in bath 59" and finally perforated by a perforating knife 58'.

Fig. 11 illustrates that [the order of perforating by perforating means 58" and tabbing by tabbing means 57" may be reversed and that either, or both, of these means may follow or precede electrolytic forming in bath 60a or 60b in tanks 59a or 59b in the presence of electrodes In any of these situations the process has in common the use of a continuous tape, and preferably formed tape or tape which is formed at some point while it is still continuous.

Many other modifications of the types described will occur to those skilled in the art and all such modifications are intended to be Within the scope and spirit of the present invention.

I claim:

1. In the electrolytic condenser art, the method of at-v taching metal tabs at intervals to a metal ribbon, perforating the metal ribbon at intervals generally. transverse to the ribbon and no more than once between any adjacent pair of metal tabs, and before severing into individual electrodes passing the ribbon through an oxideforming bath and placing a voltage between the foil and 'an electrode in the bath to cause current to flow in the ribbon, whereby an oxide coating is formed on all exposed surfaces of said-tabs and of saidribbon.

2. A ribbon of metallic foil divided into a plurality of electrode portions by transverse perforations, each portion having at least one transverse metallic tab affixed to the ribbon, the said at least one transverse metallic tab,

the edges of the perforations, and the exposed surfaces of said ribbon being formed to provide an oxide coating reel or one of the conducting rollers through a suitable in a conventional way.

thereon.

References ited in the file of this patent UNITED STATES PATENTS 280,787 Bray July 10, 1893 1,926,132 Ackerly Sept. 12, 1933 2,057,315 Robinson Oct. 13, 1936 2,122,392 Robinson et a1. June 28, 1938 2,174,071 Grupe Sept. 26, 1939 2,205,171 Kile et a1. June 18, 1940 2,297,608 Blackburn Sept. 29, 1942 2,333,966 Weiss Nov. 9, 1943 2,495,734 Katzman et a1 Jan. 31, 1950 2,532,171 Kaim -1 Nov. 28, 1950 2,604,517 Brennan July 22, 1952 2,703,781 Hesch Mar. 8, 1955 2,710,441 Heyman June 14, 1955 2,722,637 Brennan Nov. 1, 1955 

1. IN THE ELECTROLYTIC CONDENSER ART, THE METHOD OF ATTACHING METAL TABS AT INTERVALS TO A METAL RIBBON, PERFORATING THE METAL RIBBON AT INTERVALS GENERALLY TRANSVERSE TO THE RIBBON AND NO MORE THAN ONCE BETWEEN ANY ADJACENT PAIR OF METAL TABS, AND BEFORE SEVERING INTO INDIVIDUAL ELECTRODES PASSING THE RIBBON THROUGH AN OXIDEFORMING BATH AND PLACING A VOLTAGE BETWEEN THE FOIL AND AN ELECTRODE IN THE BATH TO CAUSE CURRENT TO FLOW IN THE RIBBON, WHEREBY AN OXIDE COATING IS FORMED ON ALL EXPOSED SURFACES OF SAID TABS AND OF SAID RIBBON. 